Prolonged exposure to environments with insalubrious sounds may be detrimental to hearing and may even cause deafness. Earplugs and ear protection devices have been developed to prevent harm to the eardrum and allow individuals to endure extended time in such environments without harm.
One of the first types of well-known protective earplugs in the United States was the “V-51 R”. This earplug was developed during World War II in order to provide improved hearing protection to members of the military who were subjected to the concussive sounds of gunfire, explosions, and extremely noisy work environments, such as at airports or aircraft maintenance facilities.
Today earplugs are more commonly used in manufacturing and research environments where workers' ears must be protected against very loud, acoustically “high” or treble sounds. These sounds are painful to the ear and can permanently damage a person's sense of hearing.
There have been three common ear protection devices developed to seal the ears of people against loud and harmful sounds, which may occur in environments such as a factories, laboratories, airports and during use of certain machinery. One type is a self-sufficient ear protection device with most of the device entering the ear canal, and which holds itself in position by friction between the earplug and the ear canal of the wearer. The second type of ear protection device has no involvement with the ear canal and is characterized by the requirement of an apparatus, such as a headband, to secure the device in place. The device may either fully cover the ear or seal against the inside walls of the ear. The third device comprises a combination of a form of self-sufficient earplugs coupled to an apparatus.
Self-sufficient earplugs are usually constructed of soft resilient material, cylindrical or slightly tapered and larger than the acoustical canal of the ear. By wedging the plugs into the ear canal, the exterior surface of the plugs conforms to the ear canal and the central portion of the plug inhibits the penetration of loud and harmful sounds to the ear canal. Such earplugs can be constructed by injection molding a foamable material into a die, which forms a foam body with a smooth thin skin on the outside.
The second type of device comprises ear protection devices mounted at opposing ends of a band that extends halfway about the wearer's head. Traditionally, each earplug seals against the walls of the ear, which surround the entrance to the ear canal. Although not as effective in preventing sound, the ear protection device attached to a band may consist of a full ear covering. Many people also object to inserting objects into their ear canal, as with self-sufficient ear protection devices. This device eliminates that concern. However, unlike the ear canal, which is largely cylindrical and more easily sealed against, the walls surrounding the entrance to the ear canal are of a more irregular shape. Therefore, it is much more difficult to construct a form fitting apparatus to effectively prevent the sounds from penetrating into the ear canal.
One disadvantage of self-sufficient ear protection devices are the difficulty an individual encounters when attempting to remove them. When workers handle the earplugs by grasping them, they sometimes pinch the outer skin, which causes it to crack and become irritated. Moreover, when such an earplug body is pressed into the ear canal, the skin on the plug body does not uniformly contract, so wrinkles may be created through which sound can pass to reduce the effectiveness of the earplug.
A drawback with both types of protective ear devices is the proper placement and stowage of the earplugs when not in use. When the noise level is not high, workers often wish to remove the ear protection device from their ears to allow for better hearing of sounds and avoiding the discomfort of earplugs. Self-sufficient earplugs, however, are usually small and easily misplaced. Band earplugs are cumbersome and arduous to store and carry.
A combination of the self-sufficient and band types of ear protection was introduced to address the issue of where to place the ear protection device when not in use. This type of hybrid ear protection device was designed as self-sufficient, but coupled to an apparatus, such as a helmet or protective glasses. The ear protection devices are usually coupled to the apparatus through cords or bar attachments. The length of these attachments typically is preset and only minor alternations are possible.
This third approach does not, however, provide a secure place to stow the device when it is not in use. Additionally, it is limited because users may find that a helmet or protective glasses are not always necessary. For example, if an individual works in proximity to a loud factory area or in an airport, eye and head protection are not required, but ear protection would still be advantageous.
An additional disadvantage of the aforementioned ear protection devices is that they are unattractive. If the user perceives the appearance to be unattractive, he or she may choose to refrain from using the protector, leading to unnecessarily increased danger. It would be desirable to design such an apparatus that is inconspicuous or visually pleasing.